JVC D-VHS component vs. DTC-100 w/169time option (pictures) on D-ILA - AVS Forum
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post #1 of 24 Old 01-05-2002, 12:35 PM - Thread Starter
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This is really for D-ILA users, because of the quirky way the D-ILA handles component video


Well, I finally got around to doing it, taking a few shots showing the differences in picture using RGB (+HV) vs. Component video (YPbPr).

Below are two shots from two movies (Ghostbusters, and Caddyshack), played back from D-VHS tapes (recorded from HBO-HD).

Equipment:
  • JVC G-11 D-ILA (calibrated by William Phelps)
  • ISCO-2 anamorphic lense
  • RCA DTC-100 modified with 169time option
  • Panasonic PD1000 D-VHS deck
  • JVC DH30000 (Japanese) D-VHS deck (component out)

Signal settings where always 1080i, and all projector settings were unchanged. By the way, changing the projector settings so that the picture settings looked more equal, well, didn't work. The component video feeds never looked hardly better (if at all) than the DVD versions.

Picture 1(both movies) is the component video (YPbPr) run from the JVC D-VHS directly into the JVC D-ILA.

Picture 2 (both movies) is the component video (YPbPr) run from the JVC D-VHS directly into a Key Digital component to RGBHV transcoder

Picture 3 (both movies is the DTC-100 w/Panasonic PD1000 D-VHS playing back through the 169time option.

Thanks to Tom at JVC, I won't be doing any HD watching through component video. Even the transcoded material is now questionable.



COMPONENT VIDEO

http://www.jet-x.com/brian/caddyCP.jpg

TRANSCODED VIDEO

http://www.jet-x.com/brian/caddyTC.jpg
RGBHV DIRECT

http://www.jet-x.com/brian/caddyDTC.jpg

COMPONENT VIDEO
http://www.jet-x.com/brian/ghostCP.jpg

TRANSCODED VIDEO
http://www.jet-x.com/brian/ghostTC.jpg
RGBHV DIRECT
http://www.jet-x.com/brian/ghostDTC.jpg

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post #2 of 24 Old 01-05-2002, 02:18 PM
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I assume you prefer the picture from the RGBHV (VGA) output of the DTC100.

My Panasonic broadcast monitor (DT-M3050W) actually prefers to see a component input.

Transcoding the VGA output of the DTC100 to component via the Audio Authority 9A60 yields HD PQ of much higher quality than the Panasonic STBs.

The 169time.com modified DTC100 is THE ultimate ATSC playback system.

"Dammit Jim, I'm a doctor not an engineer."
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post #3 of 24 Old 01-05-2002, 03:30 PM
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Hands down the RGB output looks best, a bit bright but no muddy shadows.

The component and transcoded picture almost look as though they were shot with a blue filter to be night shots.
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post #4 of 24 Old 01-06-2002, 02:54 AM
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Looks like an output voltage discrepancy to me. Do you have access to a DST-50 or something to compare?

Joe
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post #5 of 24 Old 01-06-2002, 12:32 PM
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The Y-Pb-Pr format is equivalent to Y-U-V, in which Y is the lumminance signal, U is the red component ninus Y, and V is the blue component minus Y. The green component of the image is derived by a matrix in the display device. In present-day digital recordings of video, as well as in transmissions over the air and satellite feeds, it is this Y-U-V format that is used. RCA's DTC-100 transcodes the U-U-V signal format into RGB because their older HDTV sets had only RGB inputs. Display devices require RGB. RCA opted for the conversion to be done inside the DTC-100. Using an RGB-YUV transcoder to feed YUV to a display device instroduces two conversion processes: one in the transcoder and one in the display device. I would think that this should deteriorate the signal quality somewhat, and it seems that this is confirmed by the photos submitted. The double conversion process done by the use of matrixes may introduce errors of both amplitude as well as phase, resulting in inferior picture quality. In some older television sets, the final matrixing was performed at the cathode-ray tube (picture tube) by feeding the luminance signal (Y) to the control grid and the chroma-difference signals (U and V) to the cathodes. But modern display devices use a matrix to accomplish the necessary conversion of YUV to RGB. Thanks for the attention.

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post #6 of 24 Old 01-07-2002, 10:19 AM - Thread Starter
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Quote:
Originally posted by jamoka
Looks like an output voltage discrepancy to me. Do you have access to a DST-50 or something to compare?

Joe
Yes, and I tested that last night, and while the results were about 20% better than the JVC D-VHS integrated unit, it still couldn't touch the DTC-100 with modification.

Again, this is aimed really at D-ILA users, as this device is picky and doesn't work well with component video (NTSC or HD) than with RGBHV.

-Brian

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post #7 of 24 Old 01-07-2002, 10:42 AM
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"Yes, and I tested that last night, and while the results were about 20% better than the JVC D-VHS integrated unit, it still couldn't touch the DTC-100 with modification"

A 20% voltage difference would explain the problem. Is the RCA too high, or the others too low?

Joe
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post #8 of 24 Old 01-07-2002, 01:59 PM - Thread Starter
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Quote:
Originally posted by jamoka

A 20% voltage difference would explain the problem. Is the RCA too high, or the others too low?

Joe
Doubtful...

Why? Well, my Hi-Vision laserdisc set-up also looks a helluva a lot better than the component D-VHS hook ups and more like the DTC-100(Hi-Vision is running RGBHV too). That's analog HDTV, compressed, and 3-6 years old, and outputting 1035i (comparable to 1080i).

Either the JVC D-ILA does not like component video or HDTV component video, or there is something wrong with the unit

-Brian

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post #9 of 24 Old 01-08-2002, 02:40 AM
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No. It look's like a voltage problem.

bwiklem,

Try the same test - only turn down the contrast on the PJ when using the RCA until the overall brightness apears similar to the other units, then post those pics for comparison. I'll bet you see very little difference then.

Please answer - Is the RCA too high, or the others too low?

Better yet, please report the actual voltages you measured.

Joe
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post #10 of 24 Old 01-08-2002, 07:59 PM - Thread Starter
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Quote:
Originally posted by jamoka
No. It look's like a voltage problem.

bwiklem,

Try the same test - only turn down the contrast on the PJ when using the RCA until the overall brightness apears similar to the other units, then post those pics for comparison. I'll bet you see very little difference then.

Please answer - Is the RCA too high, or the others too low?

Better yet, please report the actual voltages you measured.

Joe
First, I don't have a way of measuring voltages.

Second, I find it difficult to swallow that two different decoders (JVC DH30000 and Panasonic) both hooked up to the JVC D-ILA again both via component video, and transcoded to RGBHV display that exact same crappy looking picture.

I've already experimented with picture controls, and although I can get the RCA too look almost as crappy, that is NOT what the HD signal looks like.
We're talking two different decoders hooked up via four (4) different connections, and all four look bad. Yet the VGA looks great natively on the RCA as well as the Sony MUSE decoder.

Consequently, I hooked up an X-Box and Gamecube via component as well as through the transcoder and they exhibit the same symptoms.

-Brian

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post #11 of 24 Old 01-09-2002, 02:05 AM
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The difference between the pictures is brightness. If the RCA voltage is too high (or, less likely, both the other 2 too low), problem solved. Right?

You might want to check your camera too. If that were a CRT, I'd say your "RCA picture" was blooming.

Do you have a friend with a scope?

Joe
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post #12 of 24 Old 01-12-2002, 03:28 AM
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bwiklem,

Any progress?

I took a closer look at your screenshots. The RCA is definitely clipping the whites. I remember reading here before, something about the output of that model being out of spec in some way.

This is a long shot, but was it clipping before the 169time option too? Or only after?

10 minutes with a scope would narrow it down a lot.

Joe
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post #13 of 24 Old 01-12-2002, 09:33 AM - Thread Starter
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I've been at CES all week, so no time. And I don't have access to a scope, so I can't verify.

But component video from game systems (X-box, Gamecube, PS2) looks the same: dark and not very detailed. VGA native sources look great.

RCA looked the same prior to 169time option as well.

Sorry can't be much more help

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post #14 of 24 Old 01-13-2002, 10:23 AM
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A couple of my observations regarding D-ilas and component and RGBHV inputs.

The resultant pic from either my TU 50 or 51 broadcast or HD1000 tapes is much darker and saturated looking than the output coming from my dish 6000 receiver. This is definitly a voltage issue however there seem to be no reasonably priced way to equalize the two signals to component in.

I had, at one point, had a cinematrix modded Sony 7700 player connected to the comptuter 2 RGBHV input. The signal was horribly overblown. I talked to Frank Doorhof about it and his comment was simply that the D-ilas have poor AGC, if any, on their inputs and suggested various ways of dealing with the RGBHV problem. I got tired of dealing with the whole issue and sold the player and just went back to tweaky but upgradeable HTPCs.

Everyone can make their own judgement as to how these obsevations relate to the the topic of the thread.

I happen to think it's all voltage related.

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post #15 of 24 Old 01-13-2002, 04:27 PM - Thread Starter
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Okay, must be the way the JVC D-ILA handles component video as well as component to RGB transcoding.

I took the JVC D-VHS and the component to RGB converter and hooked it up to a NEC Plasma. Night and day vs. the D-ILA. The picture on the NEC looked just like the RCA does on the D-ILA.

I guess voltage is the issue, and thus, unless there is a device that addresses voltage issues, stay away from component video devices on the D-ILA (transcoded or not)

-Brian

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post #16 of 24 Old 01-14-2002, 03:36 AM
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There may already be a device that addresses the voltage issue right inside the projector. It's possible that those levels are adjustable (maybe user-adjustable?). I'm surprised one of the DILA experts hasn't responded yet. I'll bet if you post this in the digital PJ section, someone would help.

Joe
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post #17 of 24 Old 01-15-2002, 02:58 PM
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There is a separate gain adjustment for the Component input on the projector. The adjustments are overall Gain, Red Gain, and Blue Gain. When Brian's projector was calibrated, these should have been set using an Accupel HD signal generator as the source.

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post #18 of 24 Old 01-15-2002, 03:09 PM
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anyone know of a outboard unit that corrects or equalizes the input signals? Component video that is.

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post #19 of 24 Old 01-16-2002, 07:56 AM
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I am no expert but experience the same effect off "clipped" whites and somewhat blurry picture on NEC50MP1. I feet TU-DST51 into Component (YPbPr) with HDTV signals and Sony 9000 DVD via KeyDigital converter into YPbPr+HV on Plasma. I've tested the signals way around and HDTV via KeyDigital looked worse then directly into YPbPr - blurry with some color bleed/alteration (bluish/violet shades). Need to call Key Digital about it.

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post #20 of 24 Old 01-16-2002, 01:02 PM
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This is not a simple voltage issue!

Granted, there may be compatibility issues between some DILAs and component sources.

But the DTC100 simply outputs a cleaner and more watchable picture than the Panasonic STBs. This advantage is not subtle and is true for all HD content.

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post #21 of 24 Old 01-19-2002, 04:35 AM
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"DTC100 simply outputs a cleaner and more watchable picture than the Panasonic STBs"

Cleaner and more watchable, maybe. But what about "vivid", "immersive" and "3-dimensionalityness"?:D

Those are just as important.

Joe
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post #22 of 24 Old 01-19-2002, 12:05 PM
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Quote:
Originally posted by jamoka
Cleaner and more watchable, maybe. But what about "vivid", "immersive" and "3-dimensionalityness"?:DThose are just as important.
Yup, all that good stuff!;)

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post #23 of 24 Old 01-20-2002, 03:35 PM
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Todd-

Quote:
But the DTC100 simply outputs a cleaner and more watchable picture than the Panasonic STBs. This advantage is not subtle and is true for all HD content.

Yes, there are some issues with the DST50 that make the picture different than the DTC-100 output (chroma noise). I also had this problem too with brightness, However, I discovered a way in the ECP-4000 to correct it. It was a mis adjusted HV sync board on that input. Brightness was a matter of voltage levels, particularly on the green which mostly affects the brightness. My dealer explained where on the boards of the ECP-4000 to make the adjustments. Once done, I now have all 4 of my RGBHV inputs looking identical. Also, the tuners with Y, Pr, Pb outputs are being routed through an extron transcoder for conversion to RGBHV for the projector. The calibration (for me) was not an easy one to do but since I am armed with some test equipment I was able to take a full day and get everything set up properly. Now, the outputs from my: T-1500 line doubler, DTC-100. TUDST50, Dish6000, and my DVD P scan RP56 all match in brightness and picture centering. I have 4 inputs all matched in the projector. I switch the DST50 and the RP56 that route to the Denon 5700 component switch before heading to a single input on the Extron converter and on to the ECP-4000.
Again, all my devices are now matched in brightness and contrast but I operate with this 4 input board set on the projector. If I ever had to go to another projector with one input, I believe I would opt for a transcoder like we saw Jay using. What he is doing is ultimately smart, IMHO. I was impressed with his system's ability to upconvert all devices to 1080P for the projector.

The only issue I now see with the DST50 and the 5000/mod is that these both have a higher chroma noise than either the DTC-100 or the Dish6000. But this is slight now that I have the luminance and contrast matched.


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post #24 of 24 Old 01-20-2002, 09:01 PM
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Don,

Assuming you subscribe to HBO-HD on both DISH and DirecTV, which STB has the more pleasing picture on identical content?

On my broadcast monitor it is clearly the DTC100.
Less noise, less mpeg artifact, and more pleasing (and more true to life) color decoding.

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